The present invention relates to devices to rotate down hole tubulars and, more particularly, to devices that both rotate and center down hole tubulars.
The term "down hole tubular", as used herein, refers severally to drill pipes, drill collars, casings, production tubing, and the like such as may be used in drilling and production operations.
In such operations, lengths of individual down hole tubulars are connected in order to make a string of down hole tubulars necessary for the particular application. The connection of lengths of down hole tubular to make a string is referred to as "making up" and the disconnection of a string is referred to as "breaking down". The equipment for making up and breaking down a sting of down hole tubulars is located on the surface adjacent to the drill hole typically on a drilling floor.
The making up of a string of down hole tubulars requires the lifting and aligning of an individual length of down hole tubular to be added with respect to another down hole tubular. Typically, this means that the length of down hole tubular to be added is suspended over, aligned and then connected to another down hole tubular (which may be part of a string of down hole tubulars which may be partially beneath the surface of the earth). The down hole tubular to be added may be connected to the down hole tubular already in place by threading the two of them together either directly or with a coupling. This making up operation necessarily requires that the one down hole tubular to be added must be centered and rotated with respect to the other down hole tubular while it is suspended.
Typically, several different diameters of down hole tubulars are used on an operation. For example, production tube may be 27/8 inches in diameter, drill pipe may be 3-12 inches in diameter, and casing may be up to 32 inches in diameter. As explained above, with respect to each of these different types and different diameters, it is necessary to center the down hole tubular and rotate it in order to make up a string. Accordingly, although the centering and rotating may be done by separate devices, it would be more efficient if one device could be provided that is able to both center and rotate a down hole tubular.
Prior devices suitable for handling down hole tubulars are disclosed in U.S. Pat. Nos. 4,366,606 and 269/218,238 4,403,666 which are assigned to the assignee of the present application. In the '606 patent, there is disclosed a self-centering device for clamping a down hole tubular. The '666 device is used for lifting a down hole tubular. Neither of these devices provide for rotating a down hole tubular.
One prior device known for rotating a down hole tubular resembles the '606 invention. This prior rotating device includes a pair of opposed arms similar to those used in the '606 invention for clamping. On each of these arms, the prior roller device includes a pair of rollers attached to the arm for rotating a down hole tubular. The prior rotating device may be mounted to the drilling floor adjacent the drill axis. To operate the prior rotating device, the device is first positioned with respect to the string of down hole tubulars already in place so that when the arms with the rollers close upon and engage the length of down hole tubular to be added, it will be centered with respect to the drill axis of the string of down hole tubulars already in place. Then the length of down hole tubular to be added is suspended into position, centered by the prior device and rotated by the prior device onto the existing string of down hole tubulars. Then, a wrenching device engages the down hole tubulars and tightens the lengths of down hole tubular together to the required tongue.
The prior device has several disadvantages. The size and spacing of the pair of rollers on each opposing arm can only accommodate a limited range of diameters of down hole tubulars. For small diameter down hole tubulars, the size and spacing of these rollers must be small enough so that adjacent rollers do not interfere with each other when in the closed position. For large diameter down hole tubulars, the size and spacing of these rollers must be large enough to sufficiently engage and spin a down hole tubular between opposing roller pairs. If it is necessary to rotate a down hole tubular having a diameter outside of the range accommodated by the arms and rollers on the prior device, the old set of arms and rollers must be removed and a new set of arms and rollers having a different size and spacing must be installed. This operation can be lengthy and tedious and result in an interruption of operations and detract from efficiency.
Another disadvantage of the prior device is that it has a limited capture range for centering the down hole tubular to be added with respect to the existing string of down hole tubulars. If the down hole tubular to be added is not suspended closely in line with the existing string of down hole tubulars, the prior device will not engage it when it closes. Thus, time must be spent aligning the down hole tubular to be added before it is engaged and rotated by the prior device.
Accordingly, it is an object of the present invention to provide a means for centering and rotating a down hole tubular that includes a large capture region.
It is a further object of the present invention to provide a means to center and rotate a down hole tubular with the same device.
It is yet another object of the present invention to provide a centering spinner that can accommodate down hole tubulars having a range of diameters.